Self-locking retaining ring



Nov. 6, 19 51 HE|MANN 2,574,034

SELF-LOCKING RETAINING RING Filed Aug. 30, 1949 FIG. 2

Inventor:

HEINRICH HEIMANN By W 2 Attorney Patented Nov. 6, 1951 KOL-I-NQOI', Inc.,- Long Island City, xa qn Neil-fork? M Applicatiofiifilgii'st-30, 1949; ses me. 113,171

(01. s5 's'.s'

- 3 Claims.

Thi invention "rla s to"; V 'p" selfglgcking' ai'iar h hq e o o cerned t i sel'f locking ta l nndf s a a a 'Knownselfllocking "retaining "rings e a closed ring body of tempered spring stf'pio vided with radial prongs extending inwardly for the external ring and dutwardly for the internal ring from theringbo housing"boid'ifibhd tiofi"onl$ ,'i'.'.e H rection which tends to increase the intimation of the prongs. Whenthrus'tforces in the opposite direction are applied to" the ring, the prongs t d t strai h en? Qut. with the. esul th their free ends press or e the-mate ial of the shaft orb ovide a selflocking action e. from being shifted axially-eve und'encon'sidrable thrust loadsexerted o th a ast a mach ine part located-thereby. D enning the size of-*tlie ring; the thickne bithe' ring' 'inaterial the length of the' 'p ana or the-" shearingstrength 1 of the 'surf materialof 1 thesha'ft or housing; the aiiacitv ca ssona riiig can reach several; hundred pounds. Therefore, rings of the aforesaid*- sel-fj jlocl ing type form shoulders in: installation e'te-"rustl wherein a relati elr- 16W." capaci W th n thiflist such licat s? bein li m hin y 1 9. a typew ter calcu at ma nes b s ness machines, et cetera. In such machinervit is ommon ract se t s i closed S o la having i e fit laiivelr i9 sha t 0 m s sqrthat they-n nybe Sh fted; asi ni -pb t and thereupon "locked with a set screw. finch stop-ro ler cannot be re a e he -by q f vention al open-ended retaining rings which re; qu e-asr v ..bca e of hersme s z Of S a or by the selfloclring closed rings as described; becausethelatterjean-she assembled in one direction only. Yet the stop collars-commonly employed 'require relatively high 'machining costs, hm abo tu pst a s mb a s ss b r andha-ve the; further disadvantage that the-set screws MIB FQ Q t e -e e liable t o k loose even underslight vibrations; with V the re} suit that the collars are-unable to perform their: f ttiq t s b liar 7 B oa y-st t d lan hie t ,Q -i Y-T- i to overcome the objections and disadvantages set forth aplov for self-locking-Qclosed rings and for stop s, through therprovision of a. retaming ri bofe ip v 7 position, as with conv na1a p i1 ded taining rings, and"whicli 'whn"released' will clamp itself =to--the"outer"surface of the shaft, or the inner-jstiifafi'id f the-"housing, with a friction pressure that exceeds the forces likely to be exerted on the ring by thrus'ts 'or-vihra tions, without any requirements for grooving the shaft or housing? k j w More particularlv'th invention contemplates ands aims 1136iprovi'der an open ended; spring? retaining ring which is so constructed as'todeform circularly and which is moreover capable, through its specialized desi g n,.,- o f clamping itself when stressed, i. e. spread ove'r a' shaft or contracted Q hQ i- "1 9F911 1 9 .1?- fiy 9 filfi ore t ug-h the friction force ex --ow --p s u eagainst i -s ria e in tending tqaeturn*tb sreeor u esse state.-;, l

Another 4 object =of the-1 inventionis the provision iofia "taper-ed retaining ringcapable' of clamping? itself" o 'the surface of a shaft" or '55 mousingrmeres as"*afor-(asaid; awhere'in the dimenfigums;

sions of the ring are so chosen that when the ring is spread over a shaft or contracted into a housing bore and subsequently released, it will exert enough pressure thereon as to create frictional holding forces comparable to those exerted by a conventional stop collar of corresponding size secured by a set screw.

A still further object of the'invention is the provision of a tapered clamping ring as aforesaid, characterized by a prescribed dimensioning of height of ring middle section in relation to free ring diameter, and a chosen degree of spreading or contraction, which are such as to insure adequate clamping pressure, as well as I a spreading or contracting force which can easily be governed by pliers, the latter feature being of advantage in facilitating'assembly and dis-' assembly of the ring on its shaft or in a housing V bore.

The above and other objects and features of advantage of the improved self-locking retaining of the invention will be apparent from the following detailed description, taken with the accompanying drawing illustrating variant forms which a ring of the invention may take, in

which- Fig. 1 is a plan view of an external self-locking ring in its free or unstressed state;

Fig. 2 is a cross section showing the same ring spread over a shaft;

Fig. 3 is a plan view of an internal ring in its free or unstressed state;

Fig. 4 is a cross section of a ring according to Fig. 3 contracted in a housing; and

' Fig. 5 is a plan view of an external ring with modified lugs or ears.

In the following, the open-ended self-locking retaining ring of the invention will be described in its application to light machinery, such as typewriters, calculating and business machines, et cetera (although it is not intended to be so limited), wherein stop collars secured with a set screw were employed previously. To ascertain the correct dimensions of a tapered ring, 1. e. a ring having section heights diminishing from the middle section to the free ends thereof, which when spread over a shaft or contracted into a housing bore and subsequently released, will ex, ert suflicient pressure to create friction forces comparable to those of a stop collar of comparable size, it is necessary to establish a general relationship between the degree of spreading and contracting; the ratio Neutral or free diametg Maximum section height and the ratio Maximum working stress Modulus of elasticity Starting with the well known for a curved beam,

bending equation may be transformed to the case of the tapered ring as follows:

A 1 1+p-EI (external ring) and wherein the first ratio is well known in stress analysis, i. e., bending moment=maximum working stress timesinertia moment, divided by distance c of outermost fibre from neutral axis, and wherein, in the second ratio, vh=the maximum section height ofthe ring; For rings having rectangular section,-as the present rings, the distance from the neutral axis, is /2 the section height, or

NIF

from which the second ratio derives.

There results the following formula for external rings:

l i.2: v l-i-pTE. h i The last above formulae allow a very simple dimensioning of the ratio Neutral ring diameter Maximum section height depending on a chosen unit change of ring diameter through spreading or contraction, under the assumption that the maximum working stress does not exceedthe yieldstrength. In practical application, this means that for. high tempered steel, the ratio s/E would be approximately According to the invention, the unit change of ring diameterwith spreading or contracting has been chosen asapproximately .04 (or 4%), and in no case exceeding 5%, as a basis for ring dimensioning. for two reasons: First, even for very small rings, for example,.for rings to be assembled on a 1 5'" shaft,-the degree of spreading at the ring lugs under. the condition of 4% diameter change would be approximately. .12 Don for the example of a shaft, .022, an amount that can easily be governed withpliers. Secondly, the same dimensioning leads to a force on the plier handles which .is within the normal force exerted by hand for spreading a ring on a shaft of four times thatdiameter, namely, a shaft.

Now, taking the ratiop of spreading or contracting the ring to. be .04 for the above reasons, the formula for the relation between the height (h) of the middle section to free diameter (D), which latteris the inner diameter of the external ring and the outer diameter, of the internal ring, may be read as follows'; 1

matinee Salutio 79f). th-isccuuaticn .disclosesathatr;

D; ther wor s; th es ctioa heishtet t n? shou e npr ximat r f heatres am t r .fo :b hrthaextcrn. .1 r naand internal in It wil b s rvedtnat. t eiormulas. de e o d above for both external 'and internal ringsshow theratio D/h. tome approxi a ely mano -t to in ractically. this hows tha t l eq eaw insidegreeor spreadin .01" contr cti g. thesew tion height h of,.t he ringgnayhie-proportionally increased" I I f Y h -Sec nd e uation. w ich now h ta be gvhlllatedioralcul t n m ressure. the ring can exert o i,.1- .the. urfac .is artper housingdisw or, for a ring of rectangularsectioiy it follows that this pressure increases also with the square of the section height of the ring, and as the friction hold of the ring is a direct function of pressure, so also does the friction hold increase.

Referring now to the drawings illustrating a self-locking, open-ended retaining ring designed in accordance with above, Figures 1 and 2 illustrate an external self-locking ring A of the openended or split type, the ring being stamped from spring metal and having an inner circular edge 'I and an outer circular edge I l said edges being eccentric to one another so that the section heights of the ring decrease from the middle section l2 to minimum section height I3 near the free ends of the ring, said minimum section height being approximately one-half the height of the middle section 12 and at least equal to the axial thickness of the ring body, as is conventional in prior open-ended retaining rings of the type adapted to be set into a shaft groove. Said free ends are formed as lugs or ears I4, 15, having apertures I6, I! respectively for the insertion of the working points of pliers by which the ring may be spread over a shaft to a degree necessary for producing, in the middle section I 2 of maximum section height, a working stress approaching the yield strength of the material from which the ring is made, i. e., tempered spring steel.

According to the invention, the height of the ring middle section I2 is approximately one quarter, but not less than one quarter, of the inner diameter of the ring, 1. e. the diameter of the inner circular edge H) in the unstressed state of.

the ring. Under this condition, the yield strength d? .oiethe.material,:;as.-exp1ained .iir ethe'.-introductcry analysisais.reachedwhenthenegree of spreading inidiameter direction.approaches...4%s Then he holding forcelof theering against axial di p ace: ment for.a.africtionzcoaefiicient of .15 (a rcasonable assumption: for friction .of. metalon metal) is 1.5. times. the-force required. to :be exerted on thehandles of the. pliers .to. spread the ring about 4%,. If; for-instance,-- this. force is 12 to- 16 pounds for small rings, the holding, force .of-w-the ring against. axial;..=.displa oement is approximately 18 to 24 pounds; .Thisxholding, .force is, .in ;srna1l installations as OnItrhe."i% shaft. of..a.typewr t r which. locates. itheppapcr guide .rolls or similar parts,.; for. example, amply sufiicient so that .a ri g. accordingto :thednvention-may be. used in; stead..of;:the .well :known collars. secured .by;; set screwswhichare apt; to shakelcose in service.

In Figure flaring: A isishown to be. spreadtover azshaf-t I8 havinggdiameter about 4%, largerthan .the .inner- :edge. :1 9 soft the ring over which it has been. shifted-.. and subsequently released; The inner ring'edgelfi grips shaft l8 all aroundwith a large forcedueto, the circular :deformation of .ethesring resulting fromaits. taper and to the special dimensions as described in the present; specification.

. The internal self-locking ring B (Fig. 3) has eccentrically arranged inner and outer circular edges I9 and 20 respectively. The height of middlesection 2| is approximately one quarterof the free diameter of outer circular edgezfl; At its free ends the ring B isprovided withlu-gs 22, 23 haying apertures 24,25, respectively, for inserting .pliers to contract the ring .in assembly or disassembly and forproducing the requisite working stress in its middlesection when contracted in its-housing-bore. The 'gap'angle, i e. the an le between the free ends-is .so chosen (about 16) that, when the ring-is contracted until. the edges of the lugs meet, the contraction is in the neighborhood of 4% of the free ring diameter. In a so dimensioned ring, the holding force of the ring when the latter is sprung into a housing of corresponding diameter is about 1.5 times the force exerted with pliers on the ring ends.

In Fig. 4, the ring B is shown to be sprung into a housing 26 whose bore has a diameter about 4% smaller than the diameter of the free outer circle 20. Thus the ring outer edge 20 grips the material of the housing bore throughout its full arcuate length, due to its tapered construction which insures circular deformation and special design as aforesaid.

In Fig. 5, the external ring C is defined by an inner circular edge 21 and an eccentrically arranged outer circular edge 28. The height of the middle section 29 is again approximately one quarter of the diameter of inner circle 21. In this embodiment lugs 30, 3| are provided with facing recesses 32, 33 instead of apertures for the insertion of pliers. This modified form of lug allows a smaller radial height of the lugs and, therefore, a certain decrease of the so-called clearance diameter of the ring, i. e. the diameter of a circle concentric to the inner ring circle and contacting the outermost points of the lugs.

Without further analysis, it will be seen that self-locking retaining rings as described achieve the objectives of this invention as set forth above. More particularly, .the invention provides a selflocking retaining ring having the conventional form of an open-ended retaining ring of the type heretofore used Only in connection with a grooved shaft or housing bore groove, and accordingly possesses the advantage of such a ring in case of assembly and disassembly. As distinguished from the conventional ring, however, the present ring requires no seating groove, but on the other hand clamps the surface of shaft or housing bore with a pressure sufficient to create a high friction gripping force, which is adequate to hold the ring in position against thrust loads or vibrations encountered or likely to be encountered in lightweight machinery.

Although the invention has been described on the basis of a ring assumed to taper from its middle section to its free ends so that it deforms circularly under the spreading and contracting condition encountered in its use, it is to be understood that a similar clamping effect of ring on shaft can be obtained with rings of uniform section height, although the latter type ring may have only point contact with the shaft.

Accordingly, as many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A self-locking retaining ring adapted to form a locating shoulder on a carrying member for securing a machine part against axial displacement and which is adapted to secure itself to the surface of said member solely by its friction grip thereon, comprising an open-ended ring body stamped from spring metal having section heights which diminish continuously from the ring middle section towards the free ends thereof, whereby it is adapted to maintain circularity in deformation, the height of the middle section being approximately one-fourth of the free diameter of the circle of the ring edge which friction-grips said'sur'face, the height'of the smallest section being approximately one-half that of the middle section and at least equal to the ringthickness, the free ends of the ring body being provided with protruding lugs for receiving the working points of pliers, said ring body being adapted to be deformed radially by' said pliers within the elasticity range of the spring metal an amount not exceeding 5% of its aforesaid free diameter.

2. A self-locking retaining ring as set forth in claim 1, wherein the ring body is adapted to be spread radially outwardly and its inner edge'provides the friction-gripping edge. 7

3. A self-locking retaining ring as set forth in claim 1, wherein the ring body is adapted to be contracted radially and its outer'edge provides the friction-gripping edge. I I

HEINRICH HEIMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 18,144 Heiermann May 13, 1930 1,119,299 Martin Dec. 1, 1914 1,675,277 Roe June 26, 1928 2,240,425 Sternb'erg Apr. 29, 1941 2,243,688 Trollen May 27, 1941 2,322,949 Lux June 29, 1943 2,491,310 Heimann Dec. 13, 1949 FOREIGN PATENTS Number Country Date 145,943 Great Britain July 8, 1920 444,882 Germany' May 27, 1927 785,957 France Aug. 23, 1935 233,427

Switzerland Oct 16, 1944 

